A technology related to an LED (light emitting diode) has made rapid progress, and the LED in recent years has reached the emitted light quantity that can secure required brightness with less power; with backed up by a long service life thereof, the LED has become popular as a vehicular light source to be substituted for a conventional bulb with a tungsten filament. Since the LED is compact and lightweight, and can emit light in stable brightness by simple control, a lamp using the LED can be necessarily configured to be compact, thin, and lightweight. Moreover, the LED has high resistance to vibration and shock; thus, in a case where it is used as a light source of a lamp equipped in a vehicle trunk lid, for example, even if a strong shock is applied thereto when the trunk lid is closed, no LED is broken unlike the filament of the conventional bulb. In other words, the LED can be used as the light source of the lamp equipped in a movable part such as the trunk lid without requiring a special shock absorbing member. For this reason, the LED is suitable for a light source of an in-vehicle lamp.
FIG. 17 shows an example of installing a tail lamp 100 finished to be thin using the above LED in a trunk lid 101. Note that FIG. 18 shows in comparison an example in which a tail lamp 102 that uses the conventional bulb is arranged in the vehicle body side.
The use of the LED allows the tail lamp 100 to be thin, which enlarges the capacity of a trunk. In addition, when part of the thinned tail lamp 100 is arranged in the trunk lid 101 side, an opening W of the trunk lid 101 especially at the rear part of the vehicle can be enlarged as compared with the opening w shown in FIG. 18, which is favorable for loading/unloading of large luggage.
At this time, in a case where a wiring supplying power to the LED serving as the light source of the tail lamp 100 is routed with a detour from the vehicle body to the tail lamp 100 on the trunk lid 101 via a hinge part of the trunk lid 101, a member for protecting this wiring becomes necessary from avoiding damage to the wiring and a point of view on design (appearance). Therefore, it is preferable to be fed directly in a non-contact manner from the vehicle body side while eliminating a feeding wiring routed in the trunk lid 101 to the LED of the tail lamp 100.
In order to light this LED, a DC/DC converter to control an applied voltage and a conducting current to a proper value is conveniently used; thus, for this DC/DC converter, when the one configured to allow separation of the primary side and the secondary side of a transformer is used, it is possible to install the primary side in the vehicle body side, and the second side in the trunk lid side, respectively.
FIG. 19 shows an example of a lighting device for lighting the LED serving as the light source of the tail lamp 100 of FIG. 17. A primary side constitution unit 103 of the DC/DC converter used in the lighting device is arranged in the vehicle body side, and a secondary side constitution unit 104 is arranged in the trunk lid 101 side. When the trunk lid 101 is opened, the primary side constitution unit 103 and the secondary side constitution unit 104 are separated from each other. With the use of the lighting device configured to allow separation of the primary side constitution unit 103 and secondary side constitution unit 104, a wiring routed with a detour and a member for protecting this wiring can be reduced. Then, an appearance on design inside the trunk can be preserved.
Note that as a matter of course, even in the DC/DC converter separated in the primary and secondary sides, it is necessary to control an output power thereof appropriately. In a DC/DC converter having a configuration as shown in FIG. 19, a conventional example that performs control of the primary side while a state of supply power to a load connected to the secondary side is transmitted from the secondary side to the first side (fed back) will be described below.